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In this work, the authors have successfitlly synthesised amorphous mesoporous magnesium silicate particles by the sol-gel technique combining with block copolymer P123 (EO^sub 20^PO^sub 70^EO^sub 20^) as a template. Mesoporous magnesium silicate particles were characterised by X-ray diffraction, transmission electron microscopy, N^sub 2^ adsorption-desorption technique, element mapping and energy-dispersive X-ray spectroscopy analysis. The results indicated that homogeneous amorphous mesoporous magnesium silicate particles have 298.4 m^sub 2^/g of specific surface area and 5.5 nm of mesoporous channels. Using rhodamine B (RhoB) as a model dye, the adsorption capacity on mesoporous magnesium silicate particles can be estimated to 190 mg/g, and the regenerated particles also exhibited good adsorption performance. Therefore these mesoporous magnesium silicate particles have potential as adsorbents for the removal of dyes from water.
1. Introduction: The removal of dyes from effluents has been extensively studied by various treatments, such as adsorption [15], chemical coagulation [6, 7], photodegradation [8-10] and biodegradation [11], Among these treatments, the adsorption method is an attractive treatment. To date, inorganic adsorbents have gained more attention to remove the dyes from water owing to their high efficacy, ease of use, environmental friendliness, and so on [3-5, 12-14], For example, activated carbon is an effective and the most used inorganic adsorbent for the removal of organic pollutants in practical applications owing to its high adsorption capacity, despite it being an expensive material [12, 13].
In recent years, many efforts have been made to find effective and cheap inorganic adsorbents. Magnesium silicate as a candidate has been attracting growing interest for the removal of organic pollutants [ 14 -17]. It has been demonstrated that the surface of magnesium silicate is negatively charged because of the free hydroxyl groups on the surface, and the charge can be balanced by hydrated cations [15]. Hence, cationic dyes can be attracted by the anionic sites of the surface and the adsorption can be improved by ion exchange. Therefore high specific surface area could provide more reactive sites for dye adsorption. On the other hand, high porosity with suitable pore size is also necessary to enhance the accessibility of dyes to reactive sites. Therefore to enhance the dye adsorption capacity on magnesium silicate, one of the effective strategies is to synthesise magnesium silicate with high specific surface...